Control apparatus



Nov. 30, 1948. D. M. BORDEN v 2,455,292

CONTROL APARATUs Filed April 13, 1944.

m l N Patented Nov. 30, w48

-U NITE-D s 'raras harem oF-fries inaviaM. nordengnoal oas, Mich, ssignomo Chrysler Corporation, Highlandtlark, =Mich.,-a

,corporation i" Delaware Application April 13, 1944,' SerialiNoSSOlSZ is interniptedandl thesuperchargerstalls. This l condition lpuoduces noises v and `vibrations #and pulsations that may cause physical failure-of the parts.

.lf a-supercharger is to -be used only atene altitude, it is not-difficult to'fclesign'it-softlrat it may .be operated satisfactorily within v"the pumping limit. However, if the superchargeris to .he used at different altitudes, as is the case when it is part Aof an aircraft powerplann the greatly varying intake pressures cause pumping limit to occur under varying conditions, and `it is very dicult to make the superchargeroperate within the pumping limit at all times.

:It has been discovered that when pum-ping limit occurs, there isa disturbance or change in the relation of the pressures of certain. regions ofthe machine. I propose to put th'isdisturbance or change to work to takethe supercharger away from the pumping limit. i

An object of the present invention is .to provide an improved control for a supercharger;.par ticular-ly one of; theaxial` type. :Morespecically the control is .adapted to prevent. ythe supercharger.

from reachingthe pumping limit.

A further object is to..produce a'fcontrol for a supercharger for prevent-ingthe .supercharger from reaching or exceeding ,fthe pumpingelimit,

which` control operates directly upon a :phenomf enon arising., atf,al -condition ofpumpingJimit. The advantage in providing aucontrol iof this type is that it isqmore direct' and isz' less idependent on -a mazeof complications v.such as operating characteristicsof the` superchargerat varying temperatures and pressures.

Other objects will appear'from the-.disclosure The-,figure shows the invention: of the present invention partially schematically and;partially in section. supercharger l0 has analnlet end1 l l :land: a

dischargev end. I2, from which extends; ia, line.7 1.3 i'

2 leading to an enginerfnotshown. At onefipoint thei'line l3cis1a$scleQoutlet I4 vcontrolledwhy arspilliualve 1.5. @The supercharger has 1a -stationaryunemher Aor casi-ng 'i6 carryingga `plura'lity ofestationary bladestagesffspaced along the length .ofl .the casing,:of whichy only two ,stages are shown', f these 'i-being `@adjacent the inlet; end l l; 'the iirstzstage from' thelinlet venClaloe-rlg idesiga nated byi. the.referencecharacter:V l l and they secon'dwstage by mt. The-wsupercharger also :has a rotor H9 .carrying a :plurality @of rotary :blade stages 20 :placed 'alternately `between the :statienarys stages. The` rotor.Y i9 is journalledeand supported adjacent @the discharge end l2 :hy means, notshownandis driven Vloma-'shaft 2 l.

A blade 22 .of thezfirst=-stationary vlola'de stage hasan opening123i adjacent theti-pzthereof. Extending If-rom :the :,operiing 23 is ga, passage 2t extending v:ithrouglfi the blade '22 to :the iface thereof, eat whiehrapointsa line? 25 is connected.

A blade. 2S; `-of.thewrst,stationary ,bladestageA passagef'2cextends from"A they opening i 2 l to-the basefiof the blade'. 25,:.atzrwliichpoint a line .2S

isconnected.

The .fglines '125 and 29 are connected, respectively, :torchambera 3.9 sendit I f-,at opposite.; sides offa-sliaphragnr` tlfclamped `tv yits touter. periphery between: casipgcparts :B3-fand 34,which complete the@ chambers-w39 anldiB I. lz'Iheclines 42.5 zand 29;

arefzattached; respectivelm to. litt-ings; 35;-.and 3 6` threaded in openings 3l and 38 irl/.casi g.1parts 33 rand v3.4. .'TheccasinggL-part 1- y33" hasta `tubular extension; 39 ainfwhichis 1xedly;mounted a sleeve 40 ahavingia Wide .,q'aortaI ll l eat loneesideaand, narrcwcports .ft2 aandidsspaced. from goneanother atzthe; opposite side. TIn. the .sleeve-4t is-sl-idahly mounted a'piston:device:Ailv having a long section 115k having 1a rounded end46.connected to the diaphragm v-'32,--an. intermediate t section 41, yand a ,vshortsection-A. YA reduced section Jl@ is .be-- tween the sections 45 andfland a reducedsectioni betweenvthesections#Land 48. ,-Dmm

linesiilfandware connected to the; tubular exa, ,9a-at the; lportsi'AZ,y and tfrefspectivelyi Af-ttps'S fthreadedine an openingfttin. the.

tensio tubular f.- extension .23.9 .at the-portati. To: the fitting f 5.4- Aisl attached'4 aLl-inesgEE' ileadingfto a l cylinder .f 1 in :which is l slidably, mounted .f a; piston 5l.fA,.-p'late58; closes the right fendqof-the cyl infiere 55 andra-spring 5i-acting between the piston;Y and-the plate vruses .the'hston to the' left. `The piston -51r has .af stem 69, to which isconnected @a dink l161, @tor-which :is .connected an .Anprea 3 sure line 63, having a restriction 64, leads to the cylinder 56. The pressure line 63 is connected to a source of fluid pressure.

During normal operation of the supercharger ||l wit-hin the pumping limit the pressure existing at the root of the stationary blade stage l1 is equal to or perhaps slightly in excess of the pressure at the tip thereof. Ihus the pressure at the opening'21 in the blade 2t is equal to that at the 'opening 23 in the blade 22, and the pressure communicated from these openings through the lines and 29 to the chambers 35 and 3l are equal. As

. a consequence, the diaphragm 32 is in the position shown, and the section41 of the piston device 44 closes the port 4|, preventing escape of fluid under pressure from the line 55 to either of the drain lines 5i and 52. With no escape of fluid at the port 4| taking place, fluid supplied through the pressure line 63 to the cylinder 5S and the line 55 is at a maximum and the piston 51 is at an extreme position to the right so as to act through the stem 6B, the link 6|, and the arm 62 to hold the spill valve l5 in tlie'closed position.

When pumping limit is reached or approached, the pressure at the tip of the stationary blade stage I1 drops without-a corresponding drop atI therootthereof, because of the condition of stall arising at the tip.. Thus. the pressure in the chamber 3D drops, causing the diaphragm 32 to move downwardly and to bring about a downward movement of the piston device 44. The piston section 41 now at least partially uncovers the port 4|, and fluid under pressure may escape Yfrom the line 55 past the reducedisection 49 to the drain line 5|. This reduces the pressure in the piston 56, permitting the spring 59 to move the piston 51 to the left. The spill gate l5 is thereby rotated clockwise to an open position in which the spill gate spills air from the delivery line I3.V

This action prevents it from exceeding the pumping limit by increasing the now of air through the supercharger and providing an upper limit to the ratio of delivery pressure to intake pressure. This return to normal is reflected in an equalization in the pressures at the root and tip of the sta-V tionary blade stage Il'. The resultant equalizing of pressures in the chambers and 3| moves vthe diaphragm 3D and the piston device 44 upwardly.

The piston section 41 closes the port 4|, and the pressure in the cylinder 55 is `increased to move the piston 51 to the right causing the spill gate` ment of the diaphragm 32 from the positionl shown due to thefact that the pressure in chamber 3| is greater than that in the chamber'Bll.

In some superchargers vthe condition of stall upon approach or arrival of the pumping limitY may arise rst at the root of the stationary blade stage rather than at the tip thereof. Thus the pressure in chamber 3| drops, and the diaphragm 32 and the piston device 44 is raised. The section 41 at least partiallyuncovers'the port 4| so that fluid may escape from the line 55 past the reduced section 56 through the portV 43 to the drain line 52. y The resultant drop in pressure infthe cylinder 56 permits the spring 59 to move the piston 51 to the left opening the spill gate I5.

In the event that during normal operation the pressure at the tip of the blade stage l1 slightly exceeds that at the root thereof, the lower edge of the piston section 41 may be built down slighly below the lower edge of the port 4| so that the section 41 will still close the port 4| even with some small upward displacement of the diaphragm 32 shown due to the fact that the pressure in chamber 3B in greater than that in chamber 3|.

The pressure taps have been associated with blades 22 and 26 of the stationary blade stage nearest the inlet end il of the supercharger, because a condition of stall due to approach or ar- ;rival of the pumping limit generally occurs rst yTat the inlet end of the supercharger. Though location of the pressure taps at this blade stage may be desirable and advantageous, it is not an absolute necessity, for the same change in the relationship of pressures at root and tip may occur at another stationary blade stage.

The blades 22 and 26, to which the pressure taps are connected, are indicated as diametrically opposed t0 one another, but these blades -were chosen, because it simplied the problem of illustration. Actually the pressure taps may be in the same blade or in any two blades in the samestationary stage whether adjacent one another or spaced from one another.

Itrwill be apparent from the foregoing description that a new device has been developed for keeping a supercharger away from the pumping limit or for preventing it from exceeding the pumping limit. The device operates directly from conditions arising in the supercharger on approach or arrival of pumping limit and involves the use of the change in the relation of pressures at root and tip of blade staging of the supercharger for correcting the condition of pumping limit.

The intention is to limit the invention only within the scope of the appended claims.

I claim:

1. Apparatus for keeping within the pumping limit an axial flow supercharger for gas having a plurality of alternate stationary and rotary blade stages and a delivery line, the stages being generally radially coextensive with one another, said apparatus comprising means responsive to change in the relation of pressures at two points of the stationary blade stage spa-ced radially from one another upon approach or arrival of the pumping limit, a spill valve in the delivery line of the supercharger, and means connecting the aforesaid means and valve for causing the aforesaid change in the relation of pressures to increase the opening of the spill valve.

2. Apparatus for keeping within the pumping limit an axial flow supercharg-er for gas having movable blades and stationary blades having portions radially coextensive with the movable blades and a delivery line, said apparatus comprising a spill Valve in the delivery line of the supercharger, a piston connected with the spill valve, resilient means acting against the piston to increase the opening of the spill valve, means for supplying fluid under pressure to the piston to act in opposition to the resilient means to reduce the opening of the spillv valve, valve means :for reducing the pressure of the duid supplied to the piston, and means responsive to change in the relation of pressures of two points in the supercharger spaced radially from one another for causing the valve vmeans to lower the huid xpressure and thereby to increase the opening of the spill valve. 3. Apparatus for keeping within the pumping limit an axial ilow supercharger for gas having rmovable blades and stationary blades having portions radially coeXtensive with the movable blades and a delivery line, said apparatus com- .prising a spill valve in the delivery line of the supercharger, a piston connected with the spill valve, resilient means acting against the piston to increase the opening of the spill valve, means for supplying fluid under pressure to the piston to act in opposition to the resilient means to reduce the opening of the spill Valve, valve means for reducing the pressure of the fluid supplied vto the piston, a diaphragm connected with the valve means, means for supplying to one side of the diaphragm the .pressure of a first point within the superchar-ger, and means for supplying to the other side of the diaphragm the pressure of a second point within the supercharger spaced radially from the first point.

4. Apparatus for keeping within the pumping limit an axial flow super-charger for gas having movable blades and stationary blades having portions radially coextensive with the movable blades and a delivery line, said apparatus cornprising a spill valve in the delivery line of the supercharger, a piston connected with the spill valve, resilient means acting against the piston to increase the opening of the spill valve, means for supplying uid under pressure to the piston to act in o-pposition to the resilient means to reduce the opening of the spill valve, a valve adapted to occupy a central closed position or `open positions displaced in one direction or the other from the central position for reducing the pressure of the fluid supplied to the vpiston by permitting escape of the fluid, a diaphragm associated with the valve so as to be shiftable in one direction or the other from a central position to shift the valve to one `o-pen position or the other from its central position, and means for applying to opposite sides of the diaphragm the pressures of two points in the supercharger radially spaced from one another for causing a change in t'he relation of the pressures of the two points due to approach or arrival of the .pumping limit to shift the valve from closed position to one open position or the other for reducing the fluid -pressure and thereby increasing the opening of the spill valve.

5. Apparatus for controlling the operation of a supercharger having stationary blade means provided with attached base means and free tip means radially displaced from the base means, said apparatus comprising controlling means, means responsive to change in the relation of pressures at a region at the tip means and at another region at the root means due to approach or arrival of the pumping limit, and

-means `connecting the controlling means and the pressure-responsive means for causing the aforesaid change in the relation of pressures to actuate the controlling means.

6. Apparatus for keeping wit-hin the pumping limit a supercharger including stationary blades having attached bases and free tips radially spaced from the'bases and a delivery line, said apparatus comprising a spill valve in t'he delivery line of the supercharger, means responsive to 4pressure at a region at the tip of a stationary blade, means responsive to pressure at another region at the base of a stationary blade, and means connecting the spill valve and the two pressure-responsive means for causing difference in pressure between the two regions -produced by lowering -of the pressure at the tip of the iirst stationary blade due to appr-cach or arrival of the pumping limit to increase the opening of the spill valve.

7. Apparatus for keeping Within the pumping limit a compressor having a rotor and blades carried thereby and a delivery line, said apparatus comprising means responsive to changes in the relation of pressures at two points adjacent to said blades spaced radially from one another upon approach or arrival of the pumping limit, a spill valve in the delivery line of the. compressor, and means connecting the aforesaid means and valve for causing the aforesaid ychange in the relation `of pressures to increase the opening of the spill Valve.

8. Apparatus for keeping within the pumping limit a compressor having a rotor and blades carried thereby and a delivery line, said apparatus comprising a .pair of 4conduits opening at.

two points adjacent to said blades spaced radially from one another, means responsive to changes in the relation of pressures in said conduits occurring upon approach or arrival of the pumping limit, a spill valve in the delivery line of the compressor, and means connecting the aforesaid responsive means and the valve for causing the aforesaid change in the relation of pressures to increase the opening of the spill valve.

DAVID M. BORDEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 908,227 Elling Dec. 29, 1908 1,210,030 Baumann Dec. 26, 1916 2,000,721 Standerwick May 7, 1935 2,316,452 Pfenninger Apr. 13, 1943 FOREIGN PATENTS Number Country Date 19,885 Austria Apr. 25, 1905 21,310 Norway Mar. 20 1911 479,427 Great Britain Jan. 31, 1938 

